Apparatus for simultaneously electroplating inside surfaces of annular bodies

ABSTRACT

1. An apparatus for simultaneously electroplating the inside surfaces of a plurality of annular bodies arranged one above the other and with the inside surfaces in registry with each other, comprising: a plurality of seats one each interposed between any adjacent pair of said annular bodies for electrically insulating the same from each other and for keeping hermetically sealed adjacent annular bodies; an upright anode having an outer surface for forming between the outer surface and the inside surfaces of said tubular bodies a first electrolyte passage in which an electrolyte is forced to flow; a cathode conductor having individual means for electrical connection with each of said annular bodies for applying to the same a negative potential; a hat hermetically mounted on the uppermost of said seats for defining with the bodies and anode a sealed chamber; a second electrolyte passage longitudinally formed in said anode for passing therethrough an electrolyte and having a fluid communication with the first-named electrolyte passage by way of said chamber; and a detergent-air passage longitudinally formed in said anode for selectively passing therethrough a detergent and fresh air and having an outlet port extending into said chamber for cleaning said chamber and said first and second electrolyte passages, both for diluting therewith gases remaining in said chamber and for scavenging the first and second electrolyte passages, after the electroplating operation has been completed.

Oct. 15, 1974 TOSHIRQ s s ETAL 3,841,990

APPARATUS FOR SIMULTANEOUSLY ELECTROPLATING INSIDE SURFACES 0F ANNULARBODIES 7 Filed Dec. 26, 1972 2 Sheets-Sheet 1 ELECTROLYTE DETERGENT ,AIR

Oct.15, 1974 55mm 95. EI'AL 3,841,990

APPARATUS FORSIMULTANEOUSLY ELECTROPLATING INSIDE SURFACES OF AHNULARBODIES Filed Dec. 26, 1972 2 Sheets-Sheet 2 27- '0' 27 I5 26 24 IS F 7-V I 'H 1 1 /-I|| I: I III I AI A" I9 39 a il' WWI United States PatentOfiiice 3,841,990 APPARATUS FOR SIMULTANEOUSLY ELECTRO- U.S. Cl. 204-224R 7 Claims ABSTRACT OF THE DISCLOSURE Herein disclosed is an improvedapparatus for simultaneously electroplating the inside surfaces of aplurality of annular bodies. The apparatus includes an upright anodedisposed within registered bores of the annular bodies for forminginbetween a first electrolyte passage, a hat member hermetically mountedon the upper surface of the uppermost annular body for defining a sealedchamber, and a second electrolyte passage longitudinally formed in theanode for passing therethrough an electrolyte and having a fluidcommunication with the first passage by way of the chamber. Theapparatus may further include a detergent-air passage longitudinallyformed in the anode for selectively passing therethrough a detergent andfresh air and having an outlet port extending into the chamber forcleaning the chamber and the first and second electrolyte passages, andfor diluting therewith gases remaining in the chamber and for scavengingthe first and second passages, after the electroplating operation hasbeen completed.

BACKGROUND OF THE INVENTION The present invention relates to the art ofelectroplating, and more particularly to an improvement in anelectroplating apparatus for simultaneously and uniformly electroplatingthe inside surfaces of a plurality of annular bodies, such as cylindersof internal combustion engines.

In a conventional electroplating apparatus for simultaneouslyelectroplating the inside surfaces of a plurality of annular bodies, itis an established practice to pile the annular bodies one over anotherthrough a sealing seat. An anode is disposed within the bores of theannular bodies and has its outer contour equi-distantly spaced from theinside surfaces of the bodies to form inbetween an electrolyte passage.Each of the bodies is electrically connected with the negative terminalof an energy source through a lead Wire. An electrolyte is forced toflow vertically upwardly in the electrolyte passage so as to effectelectroplating on the inside surfaces. The electrolyte, then, overflowsthe upper surface of the piled annular bodies for recovery.

One of the drawbacks concomitant with the conventional apparatus is thatsince the bodies to be electro plated are maintained at an equalpotential the effective currents flowing between anode and each of thebodies are not an equal level. This is because the electric conductivityof the flowing electrolyte is not an equal level along the vertical lineof the piled bodies due to generation of gases resulting from theelectroplating operation. This fact invites inconsistency in thethickness of the electroplated layer on the inside surfaces of theannular bodies. That is, the layer thickness of the upper body has alarger value than that of the lower body. Since, therefore, thethickness of the electroplated layer should have a minimum value, thelower body has an electroplated layer of unnecessary thickness. Thisthickened Patented Oct. 15, 1974 layer must be ground later to have aproper thickness level. This fact is naturally accompanied by anelongated time period required for the electroplating operation, withthe resultantly degraded production efliciency, in addition to thebothering grinding operation. Moreover, the increased thickness of theelectroplated layer invites spare consumption of the electroplatingmaterial such as chromium and accordingly an increased production cost.

As has been described, on the other hand, the electrolyte is guided tooverflow the top surface of the piled annular bodies so as to bedischarged into an electrolyte reservoir. A hat member, which covers thetop surface of the bodies, must be provided with joints for connecting adischarge tube or the like. In addition to this complicated structure,the sealing between the hat member and the discharge tube will become acause of trouble, because the hat member must be detachably mounted onthe particular top surface for installation of the assembled annularbody structure. The degraded sealing will permit leakage of theelectrolyte and/ or the generated gases, and accordingly will produce aproblem of firing or pollution.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to provide an improved electroplating apparatus free from theabove disadvantages.

Another object of the invention is to provide an improved electroplatingapparatus for simultaneously electroplating the inside surfaces of aplurality of annular bodies.

Still another object is to provide an improved electroplating apparatus,in which an upright anode is disposed within registered bores of theannular bodies for forming inbetween a first electrolyte passage, inwhich a hat member is hermetically mounted on the upper surface of theuppermost annular body for defining a sealed chamber, and in which asecond electrolyte passage is longitudinally formed in the anode forpassing therethrough an electrolyte and has a fluid communication withthe first passage by way of the chamber.

A further object is to provide an improved electroplating apparatus ofthe above type, in which a detergent-air passage is additionally formedlongitudinally in the anode for selectively passing therethrough adetergent and fresh air and has an outlet port extending into thechamber for cleaning the chamber and the first and second electrolytepassages, and for diluting therewith gases remaining in the chamber andfor scavenging the first and second passages, after the electroplatingoperation has been completed.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of thepresent invention will be apparent from the description made inconjunction with the accompanying drawings, in which:

FIG. 1 is a partially sectional View of an electroplating apparatusaccording to the present invention, taken in the vertical line; and

FIG. 2 is a partially sectional view taken along the line 22 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS.1 and 2, an electroplating apparatus according to the present inventionis generally designated at numeral 10, which is used to simultaneouslyand uniformly electroplating a plurality of annular bodies 11 such ascylinders of internal combustion engines. The annular bodies 11, Whichare formed with inside surfaces 12 to be electroplated, are piled oneover another through an electrically insulating seat 13 in a manner tohave their bores registered with each other. That is, each of the seats13 is interposed between any adjacent pain'of the annular bodies 11 soas to electrically insulating the bodies 11 from each other and at thesame time to keep hermetically sealed joint between the adjacent pair ofthe bodies 11, thereby forming an upright tubular body (not numbered).This tubular body rests on a base plate 14 and is assembled into a blockby means of elongated bolts 15 which are held at the corners of the baseplate 14. On the top surface of the tubular body, more specifically, aremounted an annular head disc 16 and a packing 17 both formed withregistered bores, through which the bolts 15 upwardly extend. Theuppermost ends of the bolts 15 are threaded so that they are nutted upby corresponding hanging members 18 after a hat 19 has been placed onthe packing 17 with its brim portion being fastened to the bolts 15.Thus, the hat 19 is hermetically mounted on the upper surface of thetubular body through the head disc 16 and the packing 17, therebyproviding a unitary structure assembled with the tubular body and thebase plate 14.

In the outer vicinity of the tubular body is a vertically disposedcathodic conductor 22, hereafter called cathode," formed with an upperprojection 21. It should be noted here that the cathode 22 has apredetermined intrinsic resistance, as will be discussed later. Thiscathode 22 is electrically connected with each of the annular bodies 11through a fastening bolt 23. The location of the fastening bolts 23 maybe anywhere with respect to the annular bodies 11, but they should beequi-distantly spaced from any adjacent colleagues.

As better shown in FIG. 2, two guide pipes 24 are inserted intocorresponding bores formed in both the base plate 14 and the head disc16. On the upper surface of an apparatus main body 25, are anchored twoguide rods 26 which are inserted into the guide pipes 24 when it isintended to install the assembled block in position on the main body 25.This installment is finished by fastening four arms 27 which are mountedon the main body 25, as shown.

Indicated at numeral 28 is an operating handle acting to mount theprojection 21 of the cathode 22 on a cathode plate 29 for renderingelectrically conductive the connection between the cathode 22 and thecathode plate 29. This operating handle 28 is electrically connectedwith the negative terminal of an energy source (not shown) so as toapply a negative potential to the annular bodies 11.

Disposed within the registered bores 12 of the tubular body is anupright anode 31 which is anchored in the apparatus main body 25 in amanner to upwardly extend into the chamber of the hat 19 through thebore 16a of the head disc 16. This anode 31 is made of highly conductivematerial and is electrically connected with a positive terminal of theenergy source by way of an anode plate 33. It should also be noted thatthe anode 31 has its outer contour equi-distantly spaced from the insidesurfaces 12 of the tubular body, thereby forming inbetween anelectrolyte passage 35 in which an electrolyte is forced to flow. Theouter surface of the anode 31 may preferably be coated with somesuitable material 34 having a high conductivity and a sufi'icientresistance to the attacking of the flowing electrolyte. One of thematerials suitable for this purpose is lead.

The anode 31 is not solid but has another electrolyte passage 36 formedtherein and defined by an electrolyte pipe 37 which has a suflicientresistance to the attacking of the electrolyteThis electrolyte pipe 37has its upper end extending into the chamber of the hat 19, thusofiering to the electrolyte passage 36 a fluid communication with theelectrolyte passage 35 in the particular chamber. The lower end of theelectrolyte pipe 37 is, on the other hand, communicated with anelectrolyte reservoir (not shown) by way of a discharge pipe 38.

In the anode 31, there is also formed a detergent-air passage 39 forsupplying therethrough a detergent or air to the chamber of the hat 19and to the two electrolyte passages 35 and 36. After the electroplatingoperation has been completed, the detergent thus introduced acts toclean the chamber and the passages 35 and 36, while the introduced airacts partly to dilute gases remaining in the chamber and partly toscavenge the chamber and the passages. The detergent-air passage 39 hasan outlet port 43 of nozzle shape extending into the chamber. At thelower extension of the passage 39 is provided a changeover or two-wayvalve 41 which changes the connection thereof with a detergent supplyand with an air supply, respectively, through pipe branches 42a and 42b.In another modification, the detergent-air passage 39 under discussionmay be divided into two pipelets (not shown) each for detergent and airintroductions. Then, the changeover valve 41 may be dispensed with.

Indicated at numeral 44 is an electrolyte supply pipe through which anelectrolyte is supplied to the electrolyte passage 35 by way of anelectrolyte inlet port 2511 formed in the apparatus main body 25, asshown. The electrolyte supply pipe 44 is as customary provided with avalve (not shown) for allowing and inhibiting the electrolyte supply tothe passage 35. The inlet port 25a is bypassed to anelectrolyte-detergent discharge pipe 45 which is provided with achange-over or two-way valve 46. By controlling this change-over valve46, an electrolyte and/ or detergent remaining in the passage 35 and theinlet port 250 are selectively discharged through pipe branches 45a and45b.

With these construction arrangements, since the anode 31 has alreadybeen electrically connected with the positive terminal of the energysource, the assembled block with piled annular bodies 11 to beelectroplated is fastened to the apparatus main body 25. Then, by manualhandling of the operating handle 23, the projection 21 of the cathode 22is electrically connected with the cathode Plate 29. In the meanwhile,the valve mounted in the electrolyte supply pipe 44 is opened, and thetwo change-over valves 46 and 41 are closed. At this stage, anelectrolyte is pumped into the electrolyte passage 35 by Way of thesupply pipe 44 and the inlet port 25a. As a result, the electrolytepassage 35 is filled with the incoming electrolyte. At this stage,electric conduction starts to take place between the annular bodies 11and the lead layer 34 applied on the anode 31, so that the insidesurfaces 12 of the bodies 11 are electroplated with the accompanying gasformation in the passage 35. The generated gases, which are in the formof tiny bubbles, are conveyed in the passage 35 by the flowingelectrolyte. Since, in this instance, the flow of the electrolyte isdirected upward, the conductivity of the electrolyte decreases as itgoes up, due to the increasing gas content. This requires a higher bathvoltage for the higher annular body 11. It should be appreciated thatthe above difiiculty is obviated in the electroplating apparatus 10 ofthe present invention by increasing the negative potential of theannular body 11 positioned at a higher level. That is, the effectiveelectric currents flowing between the anode 31 and each of the annularbodies 11 are adjusted at an equal level by compensating the electricconductivity of the electrolyte in the passage 35 differs along the axisof the tubular body. As has been touched shortly, the cathode 22 has apredetermined intrinsic resistance of considerable value, and thenegative potential to be applied to any of the annular bodies 11 issmaller than that to the overlying body 11 by a value determined thedistance between the two adjoining fastening bolts 23. Therefore, if theintrinsic resistance of the cathode 22 is preset at a suitable value,then the resultant negative potential drop between any adjacent annularbodies 11 will compensate the increase in conductivity of theelectrolyte wetting each of the inside surfaces 12 thereof due to thedecrease in existence of the generated gases. With this condition beingsatisfied, the thickness of the obtained electroplated layer on the 5.inside surfaces 12 of the annular bodies 11 is equal along the axis ofthe tubular body.

After the electroplating operation has been completed, the valve in theelectrolyte supply pipe 44 is closed, and the change-over valve 46 inthe discharge pipe 45 is turned to have communication with the pipebranch 45b. Then, the change-over valve 41 in the pipe 39 is changed tohave communication with the pipe branch 421; so as to introducepressurized fresh air therethrough. The air thus introduced scavenge thepassage 36, the chamber in the hat 19 and the passage 35, in otherwords, the air discharges an electrolyte remaining in the latter passage35 in to the electrolyte reservoir (not shown) through the pipes 45 and45b.

After the electrolyte has been expelled out of the passage 35, the valve41 is changed to have communication with the detergent reservoir (notshown) through the pipe 42a, and at the same time the valve 46 ischanged to have communication with the detergent reservoir through thepipe 4511, as shown in FIG. 1. Then, a detergent is pumped into the pipe39 and injected into the chamber in the hat 39 through the nozzle 43.The detergent thus injected falls down in the passage 35 while cleaningthe electroplated inside surfaces 12 of the annular bodies 11, andfinally is returned to the detergent reservoir.

As has been described in the above, since the conductivity of theflowing electrolyte is uniform everywhere in the passage 35 irrespectiveof the gradual increase of the generated gases, the resultantelectroplated layers formed on the annular bodies have the samethickness. The electroplated inside surfaces 12 of the annular bodies 11need not be ground or finished to have an equal thickness, as contraryto the conventional electroplating apparatus. The time period requiredfor the electroplating operation is considerably shortened. Moreover,spare consumption of an electroplating material is remarkably reduced.

The electroplating apparatus of the present invention should also beappreciated in the point that it has its discharge pipe formed in theanode and its outlet port formed in the apparatus main body, keeping itshat hermetically mounted on the assembled annular body structure to beelectroplated. Thus, the present electroplating apparatus is free fromany joint or hose provided at the hat for discharging the remainingelectrolyte remaining in the passages of the apparatus. As a result,free emission of noxious gases generated in the apparatus is prevented,which might otherwise invite firing. The apparatus itself can be madehighly compact, providing for a simplified handling when in operation.

The present electroplating apparatus has an advantage such that with useof the detergent-air passage formed in the anode the discharge of theremaining electrolyte and cleaning the electroplated surfaces of theannular bodies can be made without opening nor removing the hat from theassembled tubular body.

Furthermore, the outlet nozzle of the detergent-air passage extendsradially outwardly thereof and accordingly is positioned outside of theelectrolyte passage in the anode. Thus, the electrolyte remaining in theelectrolyte passage in the anode is free from being diluted with theintroduced detergent during the cleaning operation.

What is claimed is:

1. An apparatus for simultaneously electroplating the inside surfaces ofa plurality of annular bodies arranged one above the other and with theinside surfaces in registry with each other, comprising: a plurality ofseats one each interposed between any adjacent pair of said annularbodies for electrically insulating the same from each other and forkeeping hermetically sealed adjacent annular bodies; an upright anodehaving an outer surface for forming between the outer surface and theinside surfaces of said tubular bodies a first electrolyte passage inwhich an electrolyte is forced to flow; a cathode conductor havingindividual means for electrical connection with each of said annularbodies for applying to the same a negative potential; a hat hermeticallymounted on the uppermost of said seats for defining with the bodies andanode a sealed chamber; a second electrolyte passage longitudinallyformed in said anode for passing therethrough an electrolyte and havinga fluid communication with the first-named electrolyte passage by way ofsaid chamber; and a detergent-air passage longitudinally formed in saidanode for selectively passing therethrough a detergent and fresh air andhaving an outlet port extending into said chamber for cleaning saidchamber and said first and second electrolyte passages, both fordiluting therewith gases remaining in said chamber and for scavengingthe first and second electrolyte passages, after the electroplatingoperation has been completed.

2. An apparatus according to claim 1, which includes control valve meansprovided at the inlet side of said detergent-air passage.

3. An apparatus according to claim 2, comprising means for supplyingdetergent and air to said detergent and air passage, said control valvebeing a two-way valve.

4. An apparatus according to claim 1, comprising anelectrolyte-detergent discharge pipe connected to said inlet port and acontrol valve in said discharge pipe.

5. An apparatus according to claim 4, wherein said control valve is atwo-way valve.

6. An apparatus according to claim 1, wherein said outlet port includesa nozzle having its passage extending radially outwardly of saiddetergent-air passage.

7. An apparatus according to claim 1, comprising a main body, said anodebeing anchored in said main body, and a portion of said second-namedelectrolyte passage being arranged in said main body.

References Cited UNITED STATES PATENTS 3,117,071 1/ 1964 Creese 204-2723,514,389 5/ 1970 Stephan et al 204-272 X 1,982,009 11/1934 McKinney eta1. 204-272 FOREIGN PATENTS 231,995 5/ 1969 USSR 204-275 20,362 10/1961Japan 204-272 JOHN H. MACK, Primary Examiner D. R. VALENTINE, AssistantExaminer U.S. Cl. X.R.

1. An apparatus for simultaneously electroplating the inside surfaces ofa plurality of annular bodies arranged one above the other and with theinside surfaces in registry with each other, comprising: a plurality ofseats one each interposed between any adjacent pair of said annularbodies for electrically insulating the same from each other and forkeeping hermetically sealed adjacent annular bodies; an upright anodehaving an outer surface for forming between the outer surface and theinside surfaces of said tubular bodies a first electrolyte passage inwhich an electrolyte is forced to flow; a cathode conductor havingindividual means for electrical connection with each of said annularbodies for applying to the same a negative potential; a hat hermeticallymounted on the uppermost of said seats for defining with the bodies andanode a sealed chamber; a second electrolyte passage longitudinallyformed in said anode for passing therethrough an electrolyte and havinga fluid communication with the first-named electrolyte passage by way ofsaid chamber; and a detergent-air passage longitudinally formed in saidanode for selectively passing therethrough a detergent and fresh air andhaving an outlet port extending into said chamber for cleaning saidchamber and said first and second electrolyte passages, both fordiluting therewith gases remaining in said chamber and for scavengingthe first and second electrolyte passages, after the electroplatingoperation has been completed.